Phased Array Feed Calibration, Beamforming and Imaging

TL;DR

This paper presents experimental results on calibrating, beamforming, and imaging with a 19-element phased array feed on a large radio telescope, demonstrating high efficiency, low noise, and interference mitigation capabilities.

Contribution

It reports practical calibration and beamforming techniques for PAFs, including adaptive filtering and sensitivity analysis, advancing their use in radio astronomy.

Findings

Aperture efficiency of 69% achieved

System noise temperature of 66 K measured

Effective interference cancellation demonstrated

Abstract

Phased array feeds (PAFs) for reflector antennas offer the potential for increased reflector field of view and faster survey speeds. To address some of the development challenges that remain for scientifically useful PAFs, including calibration and beamforming algorithms, sensitivity optimization, and demonstration of wide field of view imaging, we report experimental results from a 19 element room temperature L-band PAF mounted on the Green Bank 20-Meter Telescope. Formed beams achieved an aperture efficiency of 69% and system noise temperature of 66 K. Radio camera images of several sky regions are presented. We investigate the noise performance and sensitivity of the system as a function of elevation angle with statistically optimal beamforming and demonstrate cancelation of radio frequency interference sources with adaptive spatial filtering.